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        검색결과 170

        1.
        2021.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Meta-heuristic algorithms have been developed to efficiently solve difficult problems and obtain a global optimal solution. A common feature mimics phenomenon occurring in nature and reliably improves the solution through repetition. And at the same time, the probability is used to deviate from the regional optimal solution and approach the global optimal solution. This study compares the algorithm created based on the above common points with existed SA and HS to show advantages in time and accuracy of results. Existing algorithms have problems of low accuracy, high memory, long runtime, and ignorance. In a two-variable polynomial, the existing algorithms show that the memory increases and the accuracy decrease. In order to improve the accuracy, the new algorithm increases the number of initial inputs and increases the efficiency of the search by introducing a direction using vectors. And, in order to solve the optimization problem, the results of the last experiment were learned to show the learning effect in the next experiment. The new algorithm found a solution in a short time under the experimental conditions of long iteration counts using a two-variable polynomial and showed high accuracy. And, it shows that the learning effect is effective in repeated experiments.
        4,000원
        2.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Defining and measuring non-rigid or flexible parts has been controversial in industry for many years. There are two primary areas of controversy. The first is agreeing on what exactly a non-rigid part is. The second is agreeing on how to define and measure a non-rigid part. The subject of non-rigid parts is further complicated by the brief coverage it receives in the national and international standards. This leaves each company to improvise or create its own rules for non-rigid parts. There are some who believe that Geometrical Dimensioning and Tolerancing (GD&T) should not be used on non-rigid parts. This is not true. The ASME Y14.5M standard applies to rigid parts as a default condition. However, there is no definition given for a rigid part. The term rigid part has been used in industry for so long that it has gained a definition by its general use. When most people in industry say rigid part, they are referring to a part doesn’t move (deform or flex) when a force (including gravity) is applied. How much force is relative based on the part characteristics. In reality, all parts will deform (or flex) if enough force is applied. Using this logic, all parts would be considered non-rigid. However, we all know that this is not how parts are treated in industry. Although GD&T defaults to rigid parts, it should also be used on non-rigid parts with a few special techniques. Actually 50~60% of all products designed contain parts or features on parts that are non-rigid. Therefore, we try to suggest the definitions of rigid and non-rigid parts and method to measure non-rigid parts.
        4,000원
        3.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        One of the most performed action in daily life is standing up from sitting position. As the population of the world is aging at the high rates, people may face problems with reduced muscle strength as well as psychological changes. This can lead elderly people having difficulties with standing up from chair. Now, with the aging trend worldwide, products are being developed that can support the lives of the elderly. This study examines the distribution of hip pressure in relation to the seating positions of the standing assistance seats under development to prevent standing up accidents in older adults. The currently developing standing assistant chair designed to tilt to a maximum angle of 25 degrees. At over 25°, design considers that older people are at risk of thrown back out of that force and that the forces exerted on their arms and legs can be a significant burden to older people. By considering danger of higher than 25° for older people which is experimented in the basis of static capturing approach in previous papers, it is experimented people with age group of 20~60 on 0° to 25° tilting angle on the basis of dynamic capturing method in order to pick convenient angle of inclination. Moreover, tried to find the optimum angle by comparing the hip pressure distribution when seated at the edge of the seat and at the center of the seat with the pressure distribution sensor.
        4,000원
        4.
        2018.05 구독 인증기관·개인회원 무료
        Many studies can now confirm that the body growth of youths aged 6 to 17 is increasing due to changes in dietary habits and lifestyles in Korea. If the growth of youths increase continuously, many companies that make chairs for youths must prepare anything. Youth's chairs, which are being produced at present companies, are produced by companies with multiple data. Looking at this chair, it may not fit the body of youths of the future. It is necessary to change the design dimension of the chair for that. In this research, we try to predict how the body of youths in the future will become bigger by using physical data of youths aged 6 to 17 years old. Then, using the predicted physical data, we will propose the dimensions of the design of the chair for youth.
        5.
        2018.05 구독 인증기관·개인회원 무료
        One of the most performed actionin daily life is standing up from sitting position. As the population of the world is aging at the high rates, people may face problems with reduced muscle strength as well as psychological changes. This can lead elderly people having difficulties with standing up from chair. Now, with the aging trend worldwide, products are being developed that can support the lives of the elderly. This study examines the distribution of hip pressure in relation to the seating positions of the standing assistance seats under development to prevent standing up accidents in older adults. The currently developing standing assistant chair designed to tilt to a maximum angle of 25 degrees. At over 25°, design considers that older people are at risk of thrown back out of that force and that the forces exerted on their arms and legs can be a significant burden to older people. By considering danger of higher than 25° for older people which is experimented in the basis of static capturing approach in previous papers, it is experimented people with age group of 20~60 on 0° to 25° tilting angle on the basis of dynamic capturing method in order to pick convenient angle of inclination. Moreover, tried to find the optimum angle by comparing the hip pressure distribution when seated at the edge of the seat and at the center of the seat with the pressure distribution sensor.
        6.
        2017.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Process capability is well known in quality control literatures. Process capability refers to the uniformity of the process. Obviously, the variability in the process is a measure of the uniformity of output. It is customary to take the 6-sigma spread in the distribution of the product quality characteristic as a measure of process capability. However there is no reference of process capability when maximum material condition is applied to datum and position tolerance in GD&T (Geometric Dimensioning and Tolerancing). If there is no material condition in datum and position tolerance, process capability can be calculated as usual. If there is a material condition in a feature control frame, bonus tolerance is permissible. Bonus tolerance is an additional tolerance for a geometric control. Whenever a geometric tolerance is applied to a feature of size, and it contains an maximum material condition (or least material condition) modifier in the tolerance portion of the feature control frame, a bonus tolerance is permissible. When the maximum material condition modifier is used in the tolerance portion of the feature control frame, it means that the stated tolerance applies when the feature of size is at its maximum material condition. When actual mating size of the feature of size departs from maximum material condition (towards least material condition), an increase in the stated tolerance-equal to the amount of the departure-is permitted. This increase, or extra tolerance, is called the bonus tolerance. Another type of bonus tolerance is datum shift. Datum shift is similar to bonus tolerance. Like bonus tolerance, datum shift is an additional tolerance that is available under certain conditions. Therefore we try to propose how to calculate process capability index of position tolerance when maximum material condition is applied to datum and position tolerance.
        4,000원
        7.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        One of the challenges facing precision manufacturers is the increasing feature complexity of tight tolerance parts. All engineering drawings must account for the size, form, orientation, and location of all features to ensure manufacturability, measurability, and design intent. Geometric controls per ASME Y14.5 are typically applied to specify dimensional tolerances on engineering drawings and define size, form, orientation, and location of features. Many engineering drawings lack the necessary geometric dimensioning and tolerancing to allow for timely and accurate inspection and verification. Plus-minus tolerancing is typically ambiguous and requires extra time by engineering, programming, machining, and inspection functions to debate and agree on a single conclusion. Complex geometry can result in long inspection and verification times and put even the most sophisticated measurement equipment and processes to the test. In addition, design, manufacturing and quality engineers are often frustrated by communication errors over these features. However, an approach called profile tolerancing offers optimal definition of design intent by explicitly defining uniform boundaries around the physical geometry. It is an efficient and effective method for measurement and quality control. There are several advantages for product designers who use position and profile tolerancing instead of linear dimensioning. When design intent is conveyed unambiguously, manufacturers don’t have to field multiple question from suppliers as they design and build a process for manufacturing and inspection. Profile tolerancing, when it is applied correctly, provides manufacturing and inspection functions with unambiguously defined tolerancing. Those data are manufacturable and measurable. Customers can see cost and lead time reductions with parts that consistently meet the design intent. Components can function properly-eliminating costly rework, redesign, and missed market opportunities. However a supplier that is poised to embrace profile tolerancing will no doubt run into resistance from those who would prefer the way things have always been done. It is not just internal naysayers, but also suppliers that might fight the change. In addition, the investment for suppliers can be steep in terms of training, equipment, and software.
        4,000원
        9.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Even though cars have a good effect on modern society, traffic accidents do not. There are traffic laws that define the regulations and aim to reduce accidents from happening; nevertheless, it is hard to determine all accident causes such as road and traffic conditions, and human related factors. If a traffic accident occurs, the traffic law classifies it as ‘Negligence of Safe Driving’ for cases that are not defined by specific regulations. Meanwhile, as Korea is already growing rapidly elderly population with more than 65 years, so are the number of traffic accidents caused by this group. Therefore, we studied predictive and comparative analysis of the number of traffic accidents caused by ‘Negligence of Safe Driving’ by dividing it into two groups : All-ages and Elderly. In this paper, we used empirical monthly data from 2007 to 2015 collected by TAAS (Traffic Accident Analysis System), identified the most suitable ARIMA forecasting model by using the four steps of the Box-Jenkins method : Identification, Estimation, Diagnostics, Forecasting. The results of this study indicate that ARIMA (1, 1, 0)(0, 1, 1)12 is the most suitable forecasting model in the group of All-ages; and ARIMA (0, 1, 1)(0, 1, 1)12 is the most suitable in the group of Elderly. Then, with this fitted model, we forecasted the number of traffic accidents for 2 years of both groups. There is no large fluctuation in the group of All-ages, but the group of Elderly shows a gradual increase trend. Finally, we compared two groups in terms of the forecast, suggested a countermeasure plan to reduce traffic accidents for both groups
        4,600원
        10.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As manufacturing industries become globalized, product design affects every area of organization. The design sets the goals for a number of different departments, so if it fails to effectively communicate these goals, the entire organization is less efficient. In addition, To communicate clearly, the design must represent a product that meets its technical specification.GD&T (Geometric Dimensioning and Tolerancing) is one of the most important factors, which has an effect on efficiency of manufacture system, in designing products. However, most of designers in different industries are prone to ignore the importance of GD&T.To analyse the importance of GD&T compliance with international standards for design drawing, a comparison analysis of the difference between two methods, composite profile control and multiple single segment profile control, is performed on three different cases and suggests how it used to be more suitable.Composite profile tolerance is specified by a dual feature control frame that has one profile symbol specified with two lines of tolerance information. Whereas a multiple single segment profile control is when two or more single segment profile callouts are used to define the location and/or orientation and/or size and/or form of a part feature. In this study, the following results will be provided : a clear definition and an obvious difference of the tolerance zone, datums and datums sequence and minimization of tolerances.On this study, composite profile tolerance and multiple single segment profile tolerance were discussed. Next steps of research will consist on reaching more accurate results for profile control. Further research will be focused on dealing with the remaining 14 symbols of GD&T.
        4,000원
        12.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Optimizing energy usage for maximum efficiency is an essential goal for manufacturing plants in every industrial manufacturing sector. The generation and distribution of purifying compressed air is a large expense incurred in practically all manufacturing processes. Not only is the generation and treatment expensive equipment of compressed air, but frequent maintenance and effective operation is also required. As a plant’s compressed air system is often an integral part of the production process, it needs to be reliable, efficient, and easy to be maintain. In this paper, we study to find operating method to save energy from the adsorption dryer in the process of purifying compressed air, which is required for a clean room production site in “A” company. The compressed air passes through a pressure vessel with two “towers” filled with a material such as activated alumina, silica gel, molecular sieve or other desiccant material. This desiccant material attracts the water from the compressed air via adsorption. As the water clings to the desiccant, the desiccant particle becomes saturated. Therefore, Adsorption dryer is an extremely significant facility which removes the moisture in the air 70℃ below the dew point temperature while using a lot of energy. Also, the energy consumption of the adsorption dryer can be varied by various operating conditions (time, pressure, temperature, etc). Therefore, based on existing operating experiments, we have searched operating condition to maximize energy saving by changing operating conditions of the facility. However, due to a short experiment period (from September to October), further research will be focused on considering seasonality.
        4,300원
        13.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aging of Korea is rapidly advancing in an unprecedented rate in the world. Indoor and outdoor safety accidents involving the elderly frequently occur, with elderly population increasing. Because the physical strength of elderly is decreased, it is necessary to develop devices that aid the everyday life of the elderly to prevent safety accidents. Among many activities, the motions of standing from and sitting on a chair require much physical strength from particular body parts, which causes an overload for particular body parts. To the elderly the repeating motion of standing from and sitting down on a chair is burdensome, because they do not have enough physical strength compare to young persons . As a result the elderly could be injured or falling during standing or sitting. Therefore, the development of a lift chair that considers the problems mentioned above is necessary to prevent the safety accidents of the elderly. The study designed a non-motorized lift chair that comfortably aids the standing and sitting down motion for the use of the elderly by reflecting the anthropometric data of the Korean elderly over 65 years old. Also the design was implemented to smoothly aid the standing motion by considering the knee angle of the elderly when standing. Because the regained strength to stand from a chair is depend on the knee angle. Unlike existing lift devices, this device utilizes a tilting mechanism that does not use electric power so that the product could be composed inexpensively than existing chairs released in the market.
        4,000원
        14.
        2015.10 구독 인증기관 무료, 개인회원 유료
        With the increase in elderly population rate, interest in development of equipment to aid for the elderly activities has been increased. Since the physical features of repetitive behavior of elderly people standing and sitting can cause the stress on certain parts of the body, The necessity of developing Lift Chair concerning the foregoing problem has been to the fore. In this study, we set the average body size of the elderly aiming to develop non-motorized Lift Chair, developed Non-motorized tilting mechanism based on the Muscle strength change at knee angle, and did a study relatively inexpensive Lift Chair considering esthetic and practicality.
        4,000원
        15.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 동해 북부지역 거진, 중부지역 죽변 및 남부지역 감포의 조간대에 분포하고 있는 해조상의 지리적 종조성과 우점종 및 서식 특성을 2014년 5월과 8월에 조사하였다. 해조상의 지리적 종조성을 보면 거진, 죽변 및 감포는 모두 온대성 해조상의 특성으로서 거진은 구멍갈파래(Ulva pertusa), 염주말(Chaetomorpha moniligera)이 우점하였고, 죽변은 염주말(C. moniligera), 개서실(Chondria crassicaulis)이 우점하였다. 그리고 감포는 지충이(Sargassum thunbergii), 구멍갈파래(U. pertusa), 솜털류(Ectocarpus sp.)가 우점하였다. 지역별 해조상을 대표적으로 나타낼 수 있는 C/P, R/P와 (R+C)/P의 비율에서 거진은 각각 0.85, 2.10, 2.94, 죽변은 각각 0.58, 3.15, 3.73 그리고 감포는 각각 0.80, 3.91, 4.71로 전체 지역이 온대성 특성의 해조상이 뚜렷하게 나타났다. 군집분석의 결과에 의하면, 이들 지역은 거진의 A 그룹과 죽변과 감포 지역의 B 그룹으로 나누어졌으며, 이것은 지리적 종조성에서 죽변과 감포는 거진보다 온대성 해조상 특성이 강하게 반영되어 나타났다.
        4,000원
        16.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 동해 연안정지관측 8개 지점(감포, 울기, 장기갑, 포항, 죽변, 동해(묵호), 주문진, 속초)에서 43년(1971-2013)간 조사한 표층수온을 이용하여 지역별 수온의 유사도에 따른 군집분석과 수온의 장기 변화를 살펴보았다. 수온의 유사도에 의한 군집분석 결과, 본 연구지역은 크게 그룹 A(동해, 주문진, 속초)와 그룹 B(감포, 울기, 장기갑, 포항, 죽변)로 구분되었다. 여기서 A 그룹의 속초와 B 그룹의 죽변, 포항, 감포를 중심으로 한 수온과 수온편차의 장기 변화에서 수온은 10년 규모의 변동을 보였다. 각 지역별 수온은 43년간 증가 경향을 보였고, 1988년을 기준으로 고수온기와 저수온기로 구분되었다. 각 지역에서 43년간 수온은 속초가 2.26℃, 죽변이 1.99℃, 포항이 1.11℃, 감포는 0.89℃ 각각 증가하였고, 지역적으로는 동해 남부에서 북부로 갈수록 수온의 증가 속도가 크게 나타났다. 계절별 수온의 증가는 추계와 동계의 경우 속초>죽변>포항>감포의 순이었고, 춘계와 하계는 죽변>속초>포항>감포의 순으로 나타났다.
        4,000원
        17.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study assessed the removal efficiency of NOM which is known as the precursors of DBPs in advanced water treatment using the ceramic membrane filtration, introduced the first in the nation at the Y water treatment plant (WTP). It is generally well-known that the removal of NOM by MF Membrane is very low in water treatment process. But, the result of investigation on removal efficiency of NOM in advanced water treatment using the ceramic membrane was different as follows. The removal rate of organic contaminant by the ceramic membrane advanced water treatment was determined to be 65.5% for the DOC, 85.8% for UV254, and 77 to 86% for DBPFP. The removal rate of pre-ozonation was found to be 6 to 15% more effective compared with the pre-chlorination. The removal rate of DOC and UV254 in biological activated carbon(BAC) process was over 50% and 75%, respectively although the rate was decreased 10 ~ 20% according to analysis items in converting from GAC to BAC.
        4,000원
        18.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        토마토 접목순화장치 개발을 위한 기초실험의 일환으로 대목의 종류 및 활착실내의 온습도가 접목활착율에 미치는 영향을 조사하였다. 접목활착실의 온도는 23℃>17℃>20℃>26℃ 순으로 초기 활착율과 최종활착율이 높은 것으로 조사 되었으며, 상대습도는 높을수록 활착율은 양호한 결과를 나타냈다. 단 상대습도가 90% 이상 처리구에서는 곰팡이병에 의한 이병주 발생도 같이 증가하는 경향을 나타냈다. 대목의 종류에 따른 초기활착율은 'Kanbarune'의 26(±1)℃와 'Solution'의 20(±1)℃를 제외하고는 대목의 종류와 관계없이 모든 온도 처리구에서 83% 이상 양호한 활착율을 보였으나, 최종 활착율에서는 처리 온도간에 뚜렷한 유의적 차이를 나타내, 23(±1)℃에서만 대목의 종류와 관계없이 85%에서 90%전후의 활착율을 보였고, 20(±1)와 26(±1)℃에서는 65~75% 정도로 활착율이 저하되었다. 특히, 27(±1)℃에서는 이병주의 증가로 건묘생산율은 모든 대목처리구에서 65% 이하였다. 일반적으로 알려져 있는 고온기 접목활착 최적온도인 23(±1)℃에서는 대목의 종류에 따른 건묘생산율은 84~88% 전후로 대목 품종간 유의적 차이는 없었다. 접목활착실내 상대습도 조건에 따른 최종 접목활착율은 초기 2~3일간은 상대습도를 90%로 유지하고 나머지 7~8일간은 75% 정도로 유지하는 처리구에서 100% 접목활착 성공율을 나타냈고, 전기간 90%로 유지한 처리구와 1일 90%, 9일간은 75%로 유지한 처리구에서는 90%전후의 성공률을 나타냈다. 전반적으로 높은 상대습도 유지기간이 길수록 초기 활착율은 증가하는 경향을 보였으나, 고습도에서 장기간 묘를 양생할 경우, 곰팡이병 발생 등으로 최종 건묘생산율은 감소하므로, 초기 2~3일간만 90% 전후로 유지하고 나머지 구간은 75% 전후로 유지하는 것이 고온기 토마토 접목 활착율 향상을 위한 바람직한 조건이라 판단되었다. 각 처리간 묘소질에는 큰 차이를 나타내지 않았으나, 전반적으로 활착율이 양호했던 처리구에서 묘소질이 타 처리구에 비해 상대적으로 좋았으며, 이러한 경향은 특히 근권부의 형태적 특성을 조사한 결과에서 명료하게 나타났다. 이상의 결과 고온기 토마토 활착실내의 환경관리는 23도 전후의 온도에서 80(±5)%의 상대습도로 관리하는 것이 건묘생산에 적합할 것으로 판단되었다.
        4,000원
        19.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cleanroom could be largely classified into industrial cleanroom that can be contaminated by particles and bio-cleanroom that can be contaminated by biological particles. Electrical manufacturing companies producing precision machines and electrical parts essentially have industrial cleanroom facilities and clean technologies to produce defects free products due to particles. Industrial cleanroom should be controlled in respect of 4M1E to prevent from foreign materials of sub-micro unit and to keep out contamination sources from outside. In this paper, a concept for a quantitative methodology to measure the particles from running components was suggested by combining both newly making clean booth such as wear tester and laser particle counter.
        4,000원
        20.
        2013.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The distribution cost increases constantly because of the growth of yield, globalization of accounts and the generalization of e-commerce. This paper is concerned with scheduling on the allocation of workers to maximize the amount of order process in warehouse logistics system. The problem is to determine the number of operators in each process by the sequential time zone. We considered that the number of operators is restricted to the current level and also the process time is changed by putting some resources into the process. In each stage, we suggest some considerations for the allocation of workers and estimate the maximum amount of order process of the alternatives. We analyzed the alternatives using simulation s/w Arena with real cases.
        4,000원
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